Depending on the draws, Federer has a reasonable shot at making the SF (at worst) of every tournament and a decent shot at winning any if he avoids Nadal. This includes clay courts.

The only reason Federer's chances of winning on clay seem worse than other places is because the chances of avoiding Nadal are much lower on that surface, but the chance is still there. Take Nadal out of the way, and his chances of winning any clay tournament aren't much different than on hard courts. Federer is a great and underrated clay court player because Nadal's presence prevented him from racking up more titles and nobody cares about runner-ups that much.